The present invention is a new system that collects heat energy from the exhaust gases of a combustion engine and uses the collected thermal energy to operate hybrid vehicles or to drive the systems of a combustion engine such as the oil pump, fuel pump, water pump, alternator or the air conditioning or any other component or device that requires thermal, mechanical or electric energy. Thermal energy from the exhaust gases of combustion engines is collected in a thermal tank with phase change material to minimize the required volume and whose insulation minimizes energy losses. The connection between thermal tank and the internal combustion engine is via a heat exchanger by conduction or by convection, whichever makes a more efficient and secure setup, and minimize heat losses. Patent MX-a-2009-965 was previously obtained, for an energy collector system applicable to hybrid cars, it refers to a novel power system for hybrid vehicles in which, the energy supply is performed through a solar collector, the thermal energy is stored, and subsequently delivered to a conversion system that produces electrical energy by means of a Stirling engine, a closed cycle Brayton turbine or any other element capable of converting thermal energy into mechanical energy, such as a Rankine turbine or an open cycle air engine.
U.S. Pat. No. 5,172,784 Hybrid electric propulsion system, mentions a hybrid vehicle with an external combustion engine, that works with external heat produced by liquid fuel and does not have any thermal energy storage, therefore it does not work based on heat energy recovered from combustion engines. This way, the differences with this document is that it uses fuel to generate heat, while the proposed invention uses the energy from the exhaust gases or residual heat, then stores the heat in a tank containing phase change material. Also, the way the connection is made between the thermal tank and the heat engine is different in the proposed invention. Another document that describes a thermal tank of similar characteristics to the one used and developed by ourselves is patent Mx/a/2008/015984 which led us to see the advantages of this invention compared to the others. The invention described herein uses energy from exhaust gases making it totally different to those above mentioned devices.
In 1971 the Department of Energy (DOE) began a research on the use of Stirling engines in cars. Together with other institutions and companies such as NASA, General Motors (GM) and Stirling Thermal Motors (STM) and created prototypes of vehicles with Stirling engines and mechanical drives all the way to the tires. Technical reports show that these vehicles had properties similar to conventional cars of that era. The latest prototype of those investigations seems to be a Chevrolet Lumina '95, in a hybrid configuration (serial hybrid) a Stirling engine from STM, which generates electricity but the power source used is gasoline. Despite the earlier success, this prototype did not meet basic requirements and especially did not achieve the expected performance. During the DOE's program, research was made on the use of alternative fuels such as natural gas, however, they do not mention the use of exhaust gasses nor waste heat from any industrial process, and therefore the technical reports make it totally different to the invention presented here.
Furthermore FR 2905728 A1 and patent pending in the USPTO 20110041491, both for the inventor Thévenod, Frederic, is based on the use of a heat engine that uses the heat source with a working chamber of variable volume where reception power is for heating the working gas outside the chamber in contact with the external heat source in which the heat engine operates on a two stroke cycle in which a discharge phase, compression phase and transfer phase outgoing continue in each other in a single motion reduction chamber volume. This being completely different from the invention presented here, where energy is collected on phase change from solid to liquid in a heat insulated tank for thermal energy to be delivered through a heat exchanger preferably to a Brayton turbine driving an electric generator which charges the batteries of a hybrid vehicle. Moreover, the French Patent 2359974 and German Patent DE2729998, both of inventor Brecheisen Adell Warren refer to an internal combustion engine having a turbocharger relief mechanism, so it can work even if the exhaust gases' total energy would fall below a given value. This invention integrates to the assembly constituted by an internal combustion engine associated to an auxiliary drive device a turbocharger that receives an assistance of drive when the regime falls below a determined value. This being completely different from the invention presented here, where energy is collected on phase change from solid to liquid in a heat insulated tank for thermal energy to be delivered through a heat exchanger preferably to a Brayton turbine driving an electric generator which charges the batteries of a hybrid vehicle.
French Patent 2502692 proposes a heat recovery system for the thermal energy of the exhaust gas in an internal combustion engine. It is based on convection of a liquid, that can be water flowing through a spiral tubing around the exhaust into a thermal reservoir. This system is not based on the use of the phase change between solid and liquid media to minimize the volume required. This also has the limitation that only low temperature levels can be used, since otherwise, high pressures would be obtained. Also this patent does not involve any engine that uses the recuperated heat to aid in moving the vehicle itself or to drive its accessories. As can be seen the present invention differs fundamentally from this solution.
French Patent 2921689 “Heat recovery device for an exhaust system with integrated heat exchanger for recovering heat of exhaust gas of an internal combustion engine” discloses a heat recovery system based on convection, where a liquid, which may be water flowing through a pipe in a spiral around the exhaust passage transfers the heat to a thermal container. This system, as can be seen, is not based on the phase change material from solid to liquid to minimize storage volume. This solution is also limited to the value of the temperature at which the thermal energy is stored as the vapor pressure of the liquid leads to that the values are limited to the evaporation temperature of such liquid.
Patent application US 20160082949 A1 “System for improving exhaust gas purifying performance of diesel hybrid electric vehicle” explains a system for improving exhaust gas purification performance in which an SCR catalyst is equipped in an exhaust line to reduce nitrogen oxide within exhaust gas. This system involves a hybrid control unit to turn off an engine for the vehicle to go into hybrid driving mode and another control unit to determine if there is a request of an engine off from the hybrid control unit. However, the difference from this patent is the use of a phase change from solid to liquid in a heat-insulated tank for energy to be delivered through a system involving a turbine propelled by heat energy from the exhaust gases of a combustion engine and uses the collected thermal energy to operate a hybrid vehicle, in which the system can be coupled with that of a series or parallel hybrid vehicle. Thus, this patent is different from some others including steam turbine solutions such as U.S. Pat. No. 7,997,080 B2 Internal combustion engine with auxiliary steam power recovered from waste heat. A combination internal combustion and steam engine includes a cylinder having a piston mounted for reciprocation therein with an internal combustion chamber and a steam chamber in the cylinder adjacent; U.S. Pat. No. 8,661,817 B2 (High efficiency dual cycle internal combustion steam engine and method. The coolant in the cooling jacket of a dual cycle internal combustion steam engine is intentionally maintained at an elevated temperature that may typically range from about 225° F.-300° F. or more.) and U.S. Pat. No. 8,448,440 B2 (Method and apparatus for achieving higher thermal efficiency in a steam engine or steam expander. A high order of thermal efficiency is achieved in a steam engine or steam expander having a piston clearance that approximates zero together with a negligible amount of compression). Also, this invention is different from U.S. Pat. No. 9,276,188 B2 (Thermoelectric-based power generation systems and methods. Some embodiments provide a waste heat recovery apparatus including an exhaust tube having a cylindrical outer shell configured to contain a flow of exhaust fluid; a first heat exchanger extending through a first region of the exhaust tube, the first heat exchanger in thermal communication with the cylindrical outer shell) and similar ones using thermo-electrical components such as Peltier, Seebeck and Thomson, which are different from a Brayton Cycle turbine due to this patent achieving higher efficiency and a more compact solution.
There are several patents that mention the use of the Rankine cycle and the exhaust gas recovery:
Patent publication DE102011003607 A1 by BMW claims a method to produce mechanical power of an expansion machine using the heat of the exhaust gas of the vehicle with a feed pump on circuit run in an evaporation-pressure medium to evaporate a fluid and then to the machine for cooling and expansion in order to create mechanical work. Also, Patent US 20130174544 A1 describes a system to obtain a electric supercharged hybrid drive mechanism by means of a Rankine cycle with a heat exchanger with liquid-phase medium which is water, turbine, pipes system, a condenser and a pump. Moreover, U.S. Pat. No. 8,683,801 B2 claims a method involving a Rankine cycle of heat recovery in which the system includes a fluid going to a heat exchanger coupled to a heat source of an internal combustion engine with a conversion device in the fluid's path.
However, the proposed patent is different to all of them due to the use of a Brayton cycle turbine and a thermal tank with a phase change material to recover energy from the exhaust gas as by using this cycle there are improvements in important factors such as efficiency and the reduced size of the system.